Among the chief joys of the Royal Shakespeare Company's "A Midsummer Night's Dream" at the Kennedy Center is watching Alex Jennings watch. Jennings plays the fairy king Oberon, who, having set the night's events in motion, spends much of his stage time simply observing the mayhem he has wrought.

"He's a sick voyeur watching it all," Jennings says of the character. Fortunately for the audience, the actor's silences are as eloquent as Shakespeare's speeches; his remarkably malleable features register a parade of emotions in the course of the play. In Jennings's case, an eyebrow is worth a thousand words.

The 38-year-old actor went to drama school in Warwick, near the Stratford-Upon-Avon residence of the RSC. "Actors would come to our campus all the time and give talks and things," he recalls, running a hand through his tousled hair as he sits curled on a backstage couch at the Kennedy Center. His speech is accompanied by balletic hand gestures, and is so full of dramatic pauses that it's difficult to avoid accidentally interrupting him. "When I think back to standing in the dark in the back row at Stratford-Upon-Avon -- I couldn't afford a seat so I stood -- it's very satisfying."

Jennings, who is making his American acting debut in "Midsummer," says U.S. audiences have been "fantastically responsive" to the production. Directed by RSC head Adrian Noble and designed by Anthony Ward, the show is distinguished by its bold, simple look and an unusual willingness to acknowledge the play's vulgarity. The production has already played in San Francisco and Chicago, where Jennings says they have gotten "a much more sophisticated response than we get in England."

He suspects this may be due to British overexposure to the play rather than American savvy. "I think it's a less jaded audience," he observes. "An English audience has seen A Midsummer Night's Dream' with monotonous regularity, so they're coming to it like, What are they going to do with it this time?' "

The RSC's nontraditional staging is a far cry from the conventionally pastoral interpretations of the play. Jennings concedes that the production flaunts audience expectations. "People have to kind of leave their notions of Disneyland and Disney World and floppity rabbits behind," he says. The austere set also poses a challenge for the actors, especially in such a fantastical work. "It makes us work harder because nothing is there to be described," says Jennings. "It really does put pressure on the actors to make the language live."

In addition to lacking bunnies, this "Midsummer" is exceptionally raunchy. The play's rampant sexuality is typically glossed over in productions that emphasize the work's fairy-tale aspects, but it won't surprise anyone who has blushed his way through the text. (Shakespeare, it must be remembered, was a popular favorite in his day.) "It's pretty extreme to make your partner sleep with a donkey," Jennings notes indisputably. "There's an amorality to the fairy behavior," he continues. "They can do what they like and they do."

Six of the play's characters -- Oberon and Theseus, Titania and Hippolyta, and Puck and Philostrate -- are performed by three actors who play dual roles. Effected with minimal costume changes, this gambit italicizes the play's allusions to the duality of human nature. Jennings doesn't mind doubling up. "I don't think of them as different characters," he says. "Oberon and Titania are the sort of fairy selves of Theseus and Hippolyta; they're able to express emotions and do things to one another that they wouldn't be able to do as mortals."

Last fall, Jennings played Oberon/Theseus in the feature film of the production. Also directed by Noble, the movie was made on a limited budget -- $4 million -- in just six weeks. Though he is eager to do more film work, Jennings admits he finds the medium's lack of immediacy trying. "The process of acting is the same," he says, "but you've got to be prepared to switch it on at 5 o'clock in the afternoon when you've been in your dressing room since 7 that morning. They're ready for you, and you've got to be ready to turn it on -- that's quite frustrating."

Though the cinematic "Midsummer" is set in a "much realer world," it's not exactly realistic. Such an undertaking, Jennings maintains, would be absurd. "Some of the big {speeches} that I have are kind of like arias," he says. "The language is so rich and vivid and heightened that you can't be naturalistic about it." The actor contends that the best film adaptations of Shakespeare retain a theatrical element. Jennings hasn't seen Kenneth Branagh's "Henry V," but he is a devout fan of Laurence Olivier's version. "What's so wonderful about Olivier films is that he doesn't deny the roots," he says. "They're very theatrical films and they work."

The film version of "Midsummer" is scheduled for release early next year. The play, which opened in the summer of 1994, will do a 10-week run on Broadway after it leaves Washington. The RSC plans to revive the show when it returns to England, but with an entirely new cast. Though Jennings and the remaining original cast members have now performed the play more than 200 times, the actor hasn't yet wearied of it. "What's amazing is that the language really does keep you on your toes," he says. "You can't coast with it at all -- Shakespeare's always better than you're ever going to be." CAPTION: Alex Jennings as Oberon and Lindsay Duncan as Titania in the Royal Shakespeare's "Midsummer Night's Dream"; and Jennings in real life.